The invention relates to apparatus for monitoring redundant multi-channel analog systems in general and more particularly to such apparatus for the forming of an undisturbed mean signal value.
In the transmission of analog signals in redundant multi-channel systems the signals of the individual channels are coupled to each other without interaction and are converted into an undisturbed signal for further transmission. The signals which deviate from the probably correct signal are to be detected and eliminated. This can be accomplished by comparing the signals of each channel with the signals in each other channel. The necessary number of comparisons, however, increases much faster than the number of channels. For three channels, three comparisons are required. For four channels, this doubles to six comparisons and, for only five channels, 10 comparisons are needed. In addition, the results of these comparisons must also be compared with each other and evaluated.
A selection circuit is known which eliminates the two extreme value signals of three input signals and provides the input signal with the value between the extreme value signals at its output (British Patent 918,106). However, this known evaluation circuit cannot be expanded to more than three channels. In addition, no mean value formation between several signals takes place.